[PATCH 11/17] btrfs: Simplify btrfs_check_super_csum() and get rid of size assumptions

[Johannes Thumshirn <jthumshirn@suse.de>]

Now that we have already checked for a valid checksum type before calling
btrfs_check_super_csum(), it can be simplified even further.

While at it get rid of the implicit size assumption of the resulting
checksum as well.

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
---
 fs/btrfs/disk-io.c | 37 +++++++++++++------------------------
 1 file changed, 13 insertions(+), 24 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 74937effaed4..21ae9daf52b7 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -375,33 +375,22 @@ static int btrfs_check_super_csum(struct btrfs_fs_info *fs_info,
 {
 	struct btrfs_super_block *disk_sb =
 		(struct btrfs_super_block *)raw_disk_sb;
-	u16 csum_type = btrfs_super_csum_type(disk_sb);
-	int ret = 0;
-
-	if (!btrfs_supported_super_csum(disk_sb)) {
-		btrfs_err(fs_info, "unsupported checksum algorithm %u",
-			  csum_type);
-		ret = 1;
-	}
-
-	if (csum_type == BTRFS_CSUM_TYPE_CRC32) {
-		u32 crc = ~(u32)0;
-		char result[sizeof(crc)];
+	u32 crc = ~(u32)0;
+	char result[BTRFS_CSUM_SIZE];
 
-		/*
-		 * The super_block structure does not span the whole
-		 * BTRFS_SUPER_INFO_SIZE range, we expect that the unused space
-		 * is filled with zeros and is included in the checksum.
-		 */
-		crc = btrfs_csum_data(raw_disk_sb + BTRFS_CSUM_SIZE,
-				crc, BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE);
-		btrfs_csum_final(crc, result);
+	/*
+	 * The super_block structure does not span the whole
+	 * BTRFS_SUPER_INFO_SIZE range, we expect that the unused space
+	 * is filled with zeros and is included in the checksum.
+	 */
+	crc = btrfs_csum_data(raw_disk_sb + BTRFS_CSUM_SIZE,
+			      crc, BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE);
+	btrfs_csum_final(crc, result);
 
-		if (memcmp(raw_disk_sb, result, sizeof(result)))
-			ret = 1;
-	}
+	if (memcmp(raw_disk_sb, result, btrfs_super_csum_size(disk_sb)))
+		return 1;
 
-	return ret;
+	return 0;
 }
 
 int btrfs_verify_level_key(struct extent_buffer *eb, int level,
-- 
2.16.4